This man-made mound monument was built out of soil from all across the Polish empire.

The unsettling remnants of a torn down movie set lies nearby the ruined location of the actual Płaszów Labor Camp.

Bohemian paradise covered in majestic forests.

A church of bones, decorated with 40,000 human skeletons.

Underneath this small church are 15,000 bones, arranged by an obsessive academic.

Two stunning 17th-century libraries and a cabinet of curiosities.

The history of occult science is turned into a creepshow at this lurid Prague tourist attraction.

This quaint Hungarian railway system is operated exclusively by children between the ages of 10 and 14.

The remains of an entire Roman city can be explored in this interactive museum.

Uh, pardon me, ma'am, but I couldn't help noticing that there's a Columbo statue in the middle of Budapest.

A 19th century artistocrat's mansion, turned into a library, hidden in a modern library.

This Budapest bar allows drinkers to leave their mark on the walls, floor, and even ceiling.

Budapest's Communist-era statues, banished to the suburbs.

A marvel of technology a century ago, this disused power station now offers a lovely glimpse into the industrial design of the past.

Underneath a chalk hill in France lies what Hitler hoped would be the underground launching base for a devastating new weapon.

The former home of a trailblazing surrealist is still filled with haunting dolls and grim paintings.

A museum celebrating the Canadian forces that liberated Belgium from the Nazis replete with battlefield miniatures and multiple Gardens.

A Cold War command center is hidden under an idyllic countryside.

These crumbling Nazi artillery bunkers are now fair game for massive graffiti projects.

This ghost town in Belgium will lose its street art when it ceases to exist.

A little sculpture with a large wardrobe.

The Devil’s own choice when he needs a drink in Brussels.

A hands-off space for graffiti artists to hone and display their skills.

A long abandoned hospital building on the outskirts of NYC.